ATLANTA -- When Abby Zuniga came home Tuesday afternoon, she immediately noticed something wrong with her daughter's face; Emily Farias had a round cut just below her left eye.

"It was swollen. So when I asked her what happened to her face, she said she got shot," Zuniga said. "I was shocked."

She found out it was a BB gun that injured her daughter, one fired by a fellow middle school student aboard the school bus that afternoon.

"The driver didn't look up until he heard everybody screaming, then he only looked up for a second and looked back down," Emily said.

According to the Atlanta Police Department, a male student hid the BB gun in a bush outside of Sutton Middle School, then retrieved it before boarding the bus Tuesday afternoon. Witnesses told investigators the student accidentally shot Emily in the face and when confronted by another student, also shot that student in the back of the head.

Emily's mother told 11Alive News she was even more upset because no one from the school called her to let her know about the incident. Emily said it wasn't until she arrived at school the next day and a coach happened to ask about her injury that authorities called Atlanta Police.

Zuniga said she never spoke to anyone until she went to the school Wednesday afternoon; an email to the principal went unanswered, she said.

"A courtesy call from the administration saying, 'hey, we have your daughter here, we're aware of the situation, don't worry, we're investigating and we'll get to the bottom of it' -- I haven't gotten anything," she said.

Atlanta Public Schools spokesman Stephen Alford told 11Alive News the district is investigating the incident. He added that the principal is away on a business trip this week, and Zuniga arrived on campus Wednesday before officials had a chance to call her. Robocalls and emails were sent out Thursday afternoon, he said, and the school will send letters home to parents Friday.

The alleged shooter has been suspended from school. Atlanta police said he was arrested at school Thursday and will be charged with aggravated assault.